1. Field of the Invention
The present invention relates to a method for fabricating a circuit module that includes a substrate on which a chip component, such as a semiconductor chip, is mounted in a flip chip configuration, and more particularly, to a method for filling the gap between a substrate and a chip component with resin in a flip chip package.
2. Description of the Related Art
In flip chip package technology, in order to prevent stress on electrode bumps caused by a difference in thermal expansion coefficient between a substrate and a chip component mounted on the substrate, it is necessary to fill the gap between the substrate and the chip component in a flip chip configuration.
Resin may be applied on the entire surface of the substrate. However, if a component is incapable of operating properly when it is in contact with resin is mounted on the substrate, it is necessary to fill only the gap between the chip component and the substrate with resin.
One example of such a technique is disclosed in Japanese Unexamined Patent Application Publication No. 8-241900 which will now be briefly described with reference to FIGS. 2A to 2D. FIG. 2A illustrates a flip chip package where a chip component 2 is mounted on a substrate 1 with electrode bumps 3 disposed therebetween. As shown in FIG. 2B, a resin 6 is partially applied to the flip chip package. As shown in FIG. 2C, the resultant flip chip package is encased in a hermetically sealed enclosure 8. As shown in FIG. 2D, a pedestal 4 that is equipped with a built-in heat source heats the resin 6 while a decompressor 9 reduces the pressure inside the enclosure 8, thereby generating airflow. This airflow fills the gap between the chip component 2 and the substrate 1 with the resin 6.
Unfortunately, the technique disclosed in Japanese Unexamined Patent Application Publication No. 8-241900 has several drawbacks. That is, the technique is labor intensive since the enclosure 8 must be hermetically sealed and depressurized. Moreover, since the technique requires the decompressor 9, larger manufacturing equipment is necessary, which results in increased manufacturing costs.
Furthermore, the current trend for miniaturization of circuit modules requires a higher packing density of components on a substrate. Thus, a technique in which resin does not widely spread outside the chip components is required. Moreover, in a circuit used in a higher frequency region, if resin with a low quality factor widely spreads over the substrate, the circuit module deteriorates. Thus, the undesired spread of resin on the substrate is also a problem.